Using intact frog-eye preparations (Rana pipiens and Rana catesbiana) the back of the eyeball was exposed and a microelectrode inserted into the retina. Both the intraretinal electroretinogram (ERG) and the responses of single-ganglion cells were recorded when the eye was stimulated with light flashes in the range of 0.3- to 1.5-sec duration. The responses in the test eye were compared when this eye alone was stimulated and when both eyes were stimulated. The basic experimental design was to alternate binocular and monocular stimulation, always recording the response to the test eye. It was found that under certain circumstances the magnitude of the negative intraretinal ERG was reliably increased when stimulation to the contralateral eye accompanied the test-eye response. Control procedures indicate that this effect is the result of neural interaction between the two eyes, since it cannot be attributed to the consensual pupillary response or to such experimental artifacts as light scatter or of direct response potentials from one eye to the other.
With respect to the single-unit responses, no units were found that showed responses to contralateral stimulation alone. While there were some units that appeared to show altered response patterns as a result of concurrent contralateral stimulation, no reliable changes across units could be found in the limited sample tested.
GEORGE K. SHORTESS, "Binocular Interaction in the Frog Retina," J. Opt. Soc. Am. 53, 1423-1428 (1963)